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graphs CLIMATE-UK.COM'S REVIEW OF THE BRITISH METEOROLOGICAL SCENE
MONTHLY SUMMARY
No. 593 For MAY 2005
DRY IN THE SOUTH, PLENTIFUL SUNSHINE, SOME NOTABLE TEMPERATURE EXTREMES
Text Box: High pressure in the Iceland/Greenland region delivered cool but dry weather types to the UK between the 4th and 18th, but the anticyclone receded sufficiently to allow mainly cyclonic conditions over the British Isles from the 19th till the 28th. Mean monthly sea-level pressure was within 2 mbar of normal over the UK, but there were strong anomaly centres over southern Greenland and northern Scandinavia.

The month opened with low pressure to the southwest of the UK and a warm southerly airflow in occupation. Thunderstorms occurred widely early on the 1st, and in many western and northern districts on the following two days - a tornado caused damage in Hoghton, near Blackburn, late on the 2nd, and there was flooding in Leeds on the 3rd following 41mm of rain in 2 hours - but there were also sunny spells. The 1st was very warm with an early-morning min of 15.1C at Kenley (S London) and a max of 24.8C at Herne Bay (Kent), but it became less warm over the next few days. A rather cold and showery NW-ly flow prevailed from the 4th-9th, some of the showers were heavy and accompanied by hail and thunder, and there were overnight ground frosts.

A high pressure cell drifted east across the UK between the 10th and 12th, the showery activity diminished, most areas had prolonged sunshine by day, but nights were frosty. Early-morning minima included -3.8C at Katesbridge (Co.Down) on the 10th and -4.1C at Kinbrace (Sutherland) on the 13th. There followed a few days of easterly winds with further night frosts including a minimum of -2.7C at Kinbrace again on the 14th, but it warmed up rapidly by day and Strathallan airfield (near Perth) reached 21.4C  on the afternoon of the 15th. Ronaldsway (Isle of Man) had over 105 hrs sunshine during the eight days ending on the 14th, but much of the West Country was cold and dull with outbreaks of rain from the 13th-15th, and the maximum at Cardinham (Cornwall) on the 14th was a mere 8.4C. A renewed Arctic outbreak followed a southward-moving cold front on the 16th, and snow showers were reported in the Northern Isles and over the highlands. It became unseasonably cold again with Text Box: a maximum of just 5.5C at Kirkwall (Orkney) on the 16th, and the frosty spell culminated early on the 18th with lows of -5.8C at Dalwhinnie (Inverness-shire) and Altnaharra (Sutherland), and -6.3C at Tulloch Bridge (Lochaber) - a new UK record for the date and the lowest in the UK this late in the season since 1956.

The broad upper trough over western Europe now disrupted allowing a major change of type, and Atlantic depressions crossed Britain a frequent intervals between the 19th and 29th. After a wet day on the 19th the weather became very showery with thunder and hail in many places, and minor tornadoes were reported on the 21st in Somerset, Warwicks and Norfolk. Heavy rain affected northern and western parts of the UK on the 25th with 54.6mm in 24 hours at Sloy (Argyll), but it now became warm and humid over England and Wales for three days. On the 27th 30C was reached across much of East Anglia and Southeast England, and the high of 31.4C at Herne Bay was a new record for the date and the highest anywhere in the UK on any date in May since 1953; on the same day, however, Scotland and N.Ireland were cold and wet with maxima of 8-10C. The last few days were rather cool with sunny spells and showers, the convective activity being especially vigorous in eastern England on the 30th when several small tornadoes were noted in East Anglia.

Mean temperature ranged from 1.0 degC below normal in parts of north and west Scotland to 1 degC above in Southeast England, and overall it was the coolest May since 1996. Rainfall was above average in Scotland, N.Ireland, and scattered places in the far north of England and East Anglia, but less than half the normal amount of rain fell over much of the London area, Hampshire and Wiltshire, the middle Thames Valley and the southwest Midlands - locally here it was the seventh consecutive dry month and the driest May for 14 years. Except in some south coast counties sunshine aggregates were generally above normal - by 20-25 per cent at scattered sites in the Midlands, eastern England and eastern Scotland.
                                                                                                                                         
    TEMPERATURE   SUNSHINE   RAINFALL        
                                                                                                                                 
                                                                                                                                 
                                  Highest and lowest totals             Highest and lowest totals        
                                  on record for month    
Maximum fall in 24 hrs
   (beginning 09 h)
        on record for month    
Days with snow or sleet
 
Days with fog
(Vis <220 yards at 09 h)
 
                                                                                         
     
Difference from average
   
Difference from average
 
Highest maximum
   
Lowest minimum
   
No. of days with grass
  minimum below 0C
   
Days of no sunshine
 
Maximum duration
       
First year of record
         
Days of no rainfall
 (0.1 mm or less)
         
First year of record
         
Days with thunder
     
  PLACE  
Mean Maximum
   
Mean minimum
             
No. of air frosts
       
Total for month
                   
Total for month
                   
                               
% of average
                   
% of average
                 
                                                                     
                                   
Highest
   
Lowest
 
Year
             
Highest
   
Lowest
 
Year
       
             
Date
   
Date
         
Date
         
Year
         
Date
         
Year
           
                                                                     
    C     C     C     C           Hrs     Hrs       Hrs     Hrs       mm     mm       mm     mm          
                                                                                                                                         
  *Hampstead   16.8   +0.8   07.9   +0.3   29.8   27   02.1   11   04   00   00   11.1   27   178   098   1910   297   1989   112   1932   19   08   19   026   046   1910   124   1979   04   1989   02   00   00  
  Thorney Island   16.0   -0.6   08.1   +0.6   24.4   27   01.3   11   03   00   01   12.3   07   232   101   1958   322   1989   151   1981   15   09   19   028   066   1941   103   1946   04   1989   01   00   00  
  *Coltishall   15.8   +0.6   07.8   +0.9   24.5   27   00.7   12   02   00   00   13.7   28   177   083   1979   285   1992   141   1996   14   11   06   046   121   1964   088   2000   08   1980   05   00   00  
  *Wittering   15.6   +0.4   06.7   +0.1   27.6   27   01.1   18   06   00   00   14.0   11   232   114   1955   299   1989   133   1969   17   09   21   031   070   1955   116   1983   09   1990   04   00   00  
                                                                     
  Lyneham   15.9   +0.5   07.1   +0.5   26.5   27   01.1   11   05   00   00   12.6   12   230   115   1945   288   1990   112   1981   20   11   22   046   083   1945   139   1967   05   1990   04   00   00  
  Ross-on-Wye   16.6   +0.9   07.3   +0.1   28.0   27   00.0   11   04   00   00   14.0   23   237   127   1915   285   1992   104   1932   16   09   22   033   057   1859   158   1967   05   1896   03   00   00  
  *St Athan   15.1   +0.1   08.2   +0.9   24.5   27   03.0   09   00   00   01   13.1   11   184   089   1954   318   1990   119   1981   18   10   22   039   066   1954   155   1983   05   1991   02   00   00  
  St Mawgan   13.8   -0.3   08.2   +0.2   19.9   27   04.4   18   00   00   04   14.1   30   202   091   1956   297   1990   125   1981   13   08   21   040   069   1956   149   1981   07   1991   01   00   00  
                                                                     
  *Edgbaston   16.0   +0.9   07.8   +0.6   26.5   27   02.3   11   02   00   00   13.6   15   216   119   1887   263   1997   094   1954   18   12   21   032   058   1887   173   1932   05   1896   04   00   00  
  Valley   13.9   -0.4   08.2   +0.4   20.5   27   03.7   10   00   00   01   14.5   14   227   100   1946   306   1977   161   1970   12   06   22   033   062   1941   127   1993   10   1970   02   00   00  
  *Woodford   15.7   +0.6   06.5   +0.1   22.8   27   -02.0   11   07   01   00   13.7   14   177   095   1945   258   1989   111   1991   13   14   06   045   080   1942   144   1967   08   1991   03   00   00  
  *Watnall   15.8   +0.6   07.1   +0.5   26.3   27   01.8   17   04   00   00   13.2   12   192   095   1948   276   1989   085   1983   17   08   21   029   066   1942   135   1969   11   1991   05   00   00  
                                                                     
  *Leeming   15.6   +0.6   06.2   -0.1   20.9   02   -00.6   11   07   01   02   14.5   11   211   119   1945   238   1980   103   1983   12   08   03   043   091   1947   106   1983   09   1959   03   00   00  
  *Boulmer   14.1   +1.6   06.5   +0.7   19.8   15   01.1   18   04   00   00   13.2   13   191   108   1945   231   1989   098   1983   13   09   03   039   079   1945   151   1924   07   1992   00   00   00  
  Eskdalemuir   12.7   -0.9   04.5   +0.4   16.9   15   -02.3   11   09   06   02   14.8   13   185   112   1911   268   1935   079   1969   10   26   25   170   187   1911   257   1986   04   1984   01   00   00  
  *Bishopton   14.3   -0.7   05.6   -0.4   18.1   14   -00.3   10   08   01   03   14.1   13   202   107   1921   266   1975   098   1983   14   33   25   102   170   1921   156   1925   07   1991   01   00   00  
                                                                     
  Leuchars   13.9   +0.5   05.4   -0.4   18.1   26   -00.6   10   08   02   03   14.1   08   221   118   1922   256   1942   095   1969   11   10   01   072   149   1922   152   1969   14   1959   00   00   01  
  Dyce   12.9   +0.1   05.7   +0.6   19.3   26   01.1   11   06   00   03   14.1   12   214   123   1941   256   2001   086   1983   09   12   03   064   112   1942   152   1969   14   1994   00   00   01  
  *Stornoway   11.7   -0.5   05.2   -0.8   15.7   20   -01.6   18   05   01   00   15.0   13   181   096   1880   294   1994   093   1944   10   08   01   057   097   1943   145   1986   19   1978   00   00   00  
  *Aldergrove   13.9   -0.8   06.0   -0.1   17.6   26   -00.8   10   06   01   03   13.8   13   170   086   1927   295   1946   115   1933   12   18   18   082   165   1927   131   1993   07   1991   01   00   00  
                                                                     
                                                                                                                                         
  Stations marked with an asterisk record sunshine electronically; comparisons      
  with earlier records are therefore somewhat speculative. Thorney Island's      
  sunshine figures are from a nearby site.